WASHINGTON -- Democrats in the House of Representatives united last night to give the first big boost to President Clinton's painful prescription to shore up the nation's economy.

By a 243-183 vote that included no Republican support, the House approved a budget resolution that authorizes federal spending of $1.5 trillion in fiscal 1994 and contains the five-year .. blueprint for Mr. Clinton's program to cut the deficit and finance new investment by sharply raising taxes.

House support was almost as strong for the $16.3 billion dollar stimulus package, a short-term element of Mr. Clinton's program that became unexpectedly controversial because it calls for new spending that adds to the budget deficit.

Voting shortly after midnight, the House passed the stimulus bill on a 235 to 190 vote, picking up three Republicans.

"This is the first in a number of victories," House Majority Leader Richard A. Gephardt of Missouri told Mr. Clinton when the president called to congratulate the leadership.

Earlier, Mr. Gephardt had told his colleagues: "I think the American people are watching tonight. I think with all their hearts and all their minds, they want us to act now."

At almost that same moment, the Senate Democrats were gritting their teeth and resisting a Republican effort, in a 53-46 vote, to reject the portion of Mr. Clinton's plan that would impose a new tax on energy.

The votes in Congress were largely symbolic and do not preclude a fierce struggle in the months ahead over the energy tax and many other specific items of Mr. Clinton's proposals.

In fact, Democratic Senate opponents of the stimulus package were already marshaling their forces.

And a bipartisan group of senators voted overwhelmingly to declare themselves in firm opposition to a Clinton proposal that would raise the tax on diesel fuel used by barges on the nation's inland waterways.

But the budget deliberations being conducted on both sides of the Capitol last night reflected impressive muscle from a new president who played mightily on the legislators' desire not to be seen as obstructionists.

"The president is a very powerful lobbyist," said Rep. Charles W. Stenholm of Texas, the leader of an unsuccessful drive by moderate and conservative Democrats to trim the stimulus package by $10 billion unless other cuts were made.

"It's not a comfortable position to vote against your president and your party on the first major vote," Mr. Stenholm said, referring to a White House campaign that made loyalty the issue and left no vote to chance.

Eleven Democrats voted against Mr. Clinton on the House budget resolution. Democratic defections rose only to 22 on the stimulus vote, despite Mr. Stenholm's challenge.

Maryland's four Republicans voted against the budget resolution, while its four Democrats voted in favor of it.

Mr. Clinton called wavering House members as late as midnight Wednesday, sent letters to all of the House Democrats yesterday morning and later publicly ridiculed those who still dared to oppose him as "status quo lite."

Meanwhile, the Democratic National Committee finished making about half a million phone calls to voters around the country urging them to call their congressional representatives and demand support for the president's program.

Republicans said such voters don't really understand the contents of the president's program.

"There are only $7 billion of cuts in domestic programs over five years," said Sen. Pete V. Domenici of New Mexico, the ranking Republican on the Budget Committee.

"I can't believe Americans want to accept" nearly $300 billion in tax increases when such a small dent is being made in social spending, he said.

The House Democrats' budget calls for $264 billion in overall spending cuts, $246 billion in new taxes and more than $100 billion in new spending on long-term "investment" programs. It claims $510 billion in total deficit reductions over five years.

Republicans say the figure on overall cuts is misleading because it does not account for Mr. Clinton's new spending proposals and because the cuts come disproportionately from the Pentagon budget.

A Republican alternative offered by Ohio Rep. John R. Kasich would have achieved almost the same goal with no tax increases but with deep spending cuts. It was defeated 295-135.

Sen. Herb Kohl, a Wisconsin Democrat, agreed yesterday to take up Mr. Stenholm's failed banner against the stimulus plan in the Senate next week.

"I think it makes good sense," he said of the Stenholm amendment, which aims to limit the impact of the $16.3 billion in new spending on the budget deficit. "For God's sake, to the extent we can, let's pay for what we do."

The White House says it is determined to get Mr. Clinton's stimulus package passed intact, but the chances of that are much slimmer in the Senate.

There are 57 Democratic senators, not enough to block a filibuster by the Republicans, who are almost universally opposed to the stimulus bill.

Sen. John B. Breaux of Louisiana estimated that as many as 15 of his fellow Democrats in the Senate might not be prepared to vote for the stimulus package without changes.

But the White House said yesterday that the fight over the stimulus package seems to be only a question of whether Mr. Clinton would accept a Breaux compromise that would withhold about half of the spending until the entire Clinton plan was passed, probably in August.

Since about half of the stimulus money can't be spent before October, anyway, administration officials say privately, the Breaux compromise wouldn't have much practical effect.

Most of the stimulus money would be spent on highway and public works projects, community development programs and summer jobs for youth.

"My hope is that we can pass the president's program intact," Senate Democratic Leader George J. Mitchell of Maine said after a meeting with Mr. Clinton at the White House yesterday. "I recognize, as does the president, there may be changes."